/**
* Output the HTML needed to show the statistics graph.
*
* @param int|object $quizorid The quiz, or its ID.
* @param qubaid_condition $qubaids the question usages whose responses to analyse.
* @param string $whichattempts Which attempts constant.
*/
protected function output_statistics_graph($quizorid, $qubaids)
{
global $DB, $PAGE;
$quiz = $quizorid;
if (!is_object($quiz)) {
$quiz = $DB->get_record('quiz', array('id' => $quizorid), '*', MUST_EXIST);
}
// Load the rest of the required data.
$questions = quiz_report_get_significant_questions($quiz);
// Only load main question not sub questions.
$questionstatistics = $DB->get_records_select('question_statistics', 'hashcode = ? AND slot IS NOT NULL', [$qubaids->get_hash_code()]);
// Configure what to display.
$fieldstoplot = ['facility' => get_string('facility', 'quiz_statistics'), 'discriminativeefficiency' => get_string('discriminative_efficiency', 'quiz_statistics')];
$fieldstoplotfactor = ['facility' => 100, 'discriminativeefficiency' => 1];
// Prepare the arrays to hold the data.
$xdata = [];
foreach (array_keys($fieldstoplot) as $fieldtoplot) {
$ydata[$fieldtoplot] = [];
}
// Fill in the data for each question.
foreach ($questionstatistics as $questionstatistic) {
$number = $questions[$questionstatistic->slot]->number;
$xdata[$number] = $number;
foreach ($fieldstoplot as $fieldtoplot => $notused) {
$value = $questionstatistic->{$fieldtoplot};
if (is_null($value)) {
$value = 0;
}
$value *= $fieldstoplotfactor[$fieldtoplot];
$ydata[$fieldtoplot][$number] = number_format($value, 2);
}
}
// Create the chart.
sort($xdata);
$chart = new \core\chart_bar();
$chart->get_xaxis(0, true)->set_label(get_string('position', 'quiz_statistics'));
$chart->set_labels(array_values($xdata));
foreach ($fieldstoplot as $fieldtoplot => $notused) {
ksort($ydata[$fieldtoplot]);
$series = new \core\chart_series($fieldstoplot[$fieldtoplot], array_values($ydata[$fieldtoplot]));
$chart->add_series($series);
}
// Find max.
$max = 0;
foreach ($fieldstoplot as $fieldtoplot => $notused) {
$max = max($max, max($ydata[$fieldtoplot]));
}
// Set Y properties.
$yaxis = $chart->get_yaxis(0, true);
$yaxis->set_stepsize(10);
$yaxis->set_label('%');
$output = $PAGE->get_renderer('mod_quiz');
$graphname = get_string('statisticsreportgraph', 'quiz_statistics');
echo $output->chart($chart, $graphname);
}
/**
* Get a chart.
*
* @param string[] $labels Chart labels.
* @param int[] $data The data.
* @return \core\chart_base
*/
protected static function get_chart($labels, $data) {
$chart = new \core\chart_bar();
$chart->set_labels($labels);
$chart->get_xaxis(0, true)->set_label(get_string('grade'));
$yaxis = $chart->get_yaxis(0, true);
$yaxis->set_label(get_string('participants'));
$yaxis->set_stepsize(max(1, round(max($data) / 10)));
$series = new \core\chart_series(get_string('participants'), $data);
$chart->add_series($series);
return $chart;
}
